The touch technology, when applied to a smart terminal, enables a user to operate the terminal only by means of gesture operations. As such, a traditional mechanical keyboard is not needed, such that man-machine interaction is simpler and more direct.
However, with development of the touch technology, using capacitive touch as an example, pure finger-based touch may not accommodate user's needs in multi-dimensional inputs. Applying the force detection technology to a capacitive touch screen increases an input dimension, and enables the touch screen to sense force information of a finger, sense a force and a light press or a heavy press, and achieve different functions, such that a good user experience is provided. For example, in the touch screen force detection technology, generally, changes of an effective grounding capacitance are detected using a sensor, which, in combination with a display device, to implement touch display.
In one circumstance of the prior art, a layer of OCA adhesive is arranged on an upper surface of the middle frame of a device, and a force detection electrode is arranged on an upper surface of the layer of OCA adhesive. When being pressed by a finger, the effective grounding capacitance of the force detection electrode becomes greater. Specifically, since the distance of the force detection electrode relative to a common reference electrode (Vcom layer) in the display device changes smaller due to a press force from the finger, the effective grounding capacitance becomes greater.
In another circumstance of the prior art, a layer of OCA adhesive is arranged on a lower surface of the display device, and a force detection electrode is arranged on a lower surface of the layer of OCA adhesive. Since the distance of the force detection electrode relative to the middle frame of a mobile phone becomes smaller due to a press force from the finger, the effective grounding capacitance becomes greater. Therefore, the force given by the finger press may be calculated by detecting changes of the effective grounding capacitance.
However, a load grounding capacitor is also existed. The load grounding capacitor is formed between the force detection electrode and the middle frame, and the load grounding capacitor may cause adverse impacts to detection of the effective grounding capacitance, which causes interference to the effective grounding capacitance. In addition, the display device also causes interference to the effective grounding capacitance. Therefore, the interference may cause adverse impacts to sensitivity of detection of the effective grounding capacitance, and further lowers sensitivity of force detection.
To address the interference caused by the display device, a shielding layer is configured in the prior art. The shielding layer is arranged between the display device and the force detection electrode. However, adding such a shielding layer may increase the cost, and increase the entire thickness of the display screen. With respect to the interference caused by the load grounding capacitor, the prior art has not provided a technical solution.